1. Field of Invention
The present invention relates to fasteners in general and in particular to an improved fastener that is resistant to removal or pull-out.
2. Description of Related Art
Fasteners, such as nails, are well known for the purpose of securing articles of wood, plastic and the like together. Nails are elongate pin-shaped, sharp objects of hard metal or alloy having a sharpened end and a blunted or flared driving end.
Nails are typically driven into the work piece by a hammer, a pneumatic nail gun, or a small explosive charge or primer. A nail holds materials together by friction in an axial direction and shear strength laterally. Fasteners, such as nails, which are applied by an axial force are advantageously quick and easy to use. One limitation of nails, however is their reliance upon the friction between the nail on the wood surface to retain the nail in the material. Accordingly, nails may be prone to being axially displaced within the material which is also known as being pulled out.
Screws are also well known fasteners, however it is well known that screws are more difficult and time consuming to apply as they are required to be twisted or torque into the material. In particular, many screws are required to be axially rotated a plurality of times while being driven into the material. This is both time consuming and labor intensive. Screws also typically have a single helical thread extending therearound.
Other attempts to provide fasteners having improved pull out performance have provided circumferential rings or ridges around the shank of the nail or spiraled planar surfaces surrounding the shank of the nail, also referred to as screw-shank nails. Such attempts have similarly been limited in the resistance of the nail to pull out as the nail does not engage a surface area of the material into which it is applied that is a significantly larger than the circumference of the nail itself.